1. Field of the Invention
This invention relates to a socket for an electric part such as an IC, etc., and more particularly to a socket for an electric part in which a group of contacts provided on a socket body are operated to be in pressure contact with a downward force with a group of terminals provided on an electric part.
2. Brief Description of the Prior Art
An IC socket disclosed in U.S. Pat. No. 4,715,823, etc. includes a socket body and a contact shutter member mounted on an upper part of the socket body in such a manner as to be movable upward and downward. The contact shutter member, when pushed down, displaces the contacts backward against their elasticity to form a contact release state relative to the IC terminals so that an IC can be inserted and removed with no load in that state. The contacts, when the push-down force of the contact shutter member is released, are displaced forward due to the elasticity thereof to come into contact with the IC terminal in such a manner as to exert a downward force on a bent portion of each of the IC terminals while pushing up the contact shutter member.
In the above-mentioned socket, the contacts are displaced forward due to their elasticity and receive a contact pressure by being elastically pushed against the surface of the IC terminals, which are laterally held in a stationary state. The reliability of the contact relation between each of the corresponding IC terminals and contacts depends on only the elasticity of these contacts.
On the other hand, high density arrangements of IC terminals has progressed in recent years, and miniaturization of contacts is required now more than ever. If the contacts are miniaturized, however, the elastic coefficient inevitably becomes small, weakening their function against the IC terminals by lowering the contact pressure. As a result, a problem arises in that it is difficult to obtain a highly reliable contact relation only by means of the elasticity of the contacts.
Further, although it is desirable that the contact shutter member can be operated with as small a push-down force as possible, the reduction of the operating force in the conventional example also results in a reduction of the elastic force of individual contacts, thereby lowering the contact pressure. In other words, in the conventional example, it is difficult to reduce the push-down operating force of the contact shutter member while maintaining the contact pressure from the (elastic forces of the contacts).
The present invention has been accomplished in order to obviate the above-mentioned disadvantages inherent in the prior art.